Central European Journal of Clinical Research Volume 1, Issue 1, Pages 28-39 DOI: 10.2478/cejcr-2018-0005 REVIEW Erector Spinae Block. A narrative review. María Bermúdez López, Álvaro Gasalla Cadórniga, José Manuel López González, Enrique Domínguez Suárez, Carlos López Carballo, Francisco Pardo Sobrino Anaesthesia and Pain management Department. Hospital Universitario Lucus Augusti, Lugo, Galicia, Spain. Correspondence to: María Bermúdez López, Anaesthesia and Pain management Department. Hospital Universitario Lucus Augusti, Lugo, Galicia, Spain. E-mail: [email protected] Conflicts of interests Nothing to declare Acknowledgements None Keywords: erector spinae block; anatomy; mechanism of action; indications. These authors take responsibility for all aspects of the reliability and freedom from bias of the data pre- sented and their discussed interpretation. Central Eur J Clin Res 2018;1(1):28-39 _____________________________________________________________________________ Received: 11.07.2018, Accepted: 1.09.2018, Published: 05.09.2018 Copyright © 2018 Central European Journal of Clinical Research. This is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. agement of acute and chronic thoracic pain. ESP block is a regional anesthesia technique in Abstract which local anesthetic (LA) is injected between the erector spinae muscle and transverse pro- The erector spinae plane block is a cess under ultrasound guidance, blocking the novel ultrasound-guided technique that has re- dorsal and ventral rami of the thoracic and ab- cently been described for the management of dominal spinal nerves [1]. acute and chronic thoracic pain. Currently an In recent years a number of important increasingly number of indications for the ESP fascial plane blocks have been described block- block have been published. Nevertheless, the ing the dorsal, lateral and anterior cutaneous anatomy, mechanism of action, doses and vol- nerves of the thorax and abdomen. These new ume of local anesthetic needed are still unclear. descriptions in blocks are supposed to be an The aim of this narrative review is study this advance in regional anaesthesia due to its sim- new block with base on the updated medical plicity and lack of complications. These include literature. the transversus abdominis plane block, rectus sheath block, quadratus lumborum block, pec- Introduction toralis nerve block, serratus plane block, retrol- aminar block, and now the ESP block [1]. The erector spinae plane block (ESP The key advantage common to all of block) is a novel ultrasound-guided technique these blocks is that they are technically easier that has recently been described for the man- to perform compared with neuraxial, paraverte- 28 Regional Anaesthesia Concept bral, nerve plexus, and nerve blocks [2]. retinaculum is referred to as the thoracolumbar These plane blocks, on the other hand, fascia [10]. According to most of authors on this have lower risk for serious complications, be- topic, Willard et al.’s paper about the fascia tho- cause the injection is into tissue plane that is racolumbar [10] is required reading for anyone distant from potentially problematic structures. wishing to obtain a deeper understanding of the Since its first description by Forero et anatomical basis of this block. al. [1] there have been many articles and case This thoracolumbar fascia, extending reports including an increasingly number of in- from the posterior thorax and abdomen in con- dications for the ESP block: chronic and acute tinuity with the nuchal fascia of the neck, facili- pain treatment [1], rib fractures management in tates the spread of LA to multiple thoracic and the emergency setting [3,2], treatment abdom- lumbosacral levels during ESP blocks at lower inal surgical pain [4], hip artroplasty [5] or for thoracic levels [11]. analgesic management in breast surgery [6,7]; According to Hamilton et al, the likely as example of the rapid increase of the number anatomical basis for effective blockade occurs of papers on this matter. when LA is deposited within the erector sheath The aim of this narrative review is study [12]. The erector spinae muscles and their as- the anatomy, mechanism of action and the new sociated sheath exhibit a complex three-dimen- indications of this novel technique. It has been sional anatomy. It is similar to a paired ellipti- reported to be used in both adult and children, cal cylinders one on each side of the vertebral however, in this review we will focus on adult column. Each cylinder is surrounded by a reti- anaesthesia papers. nacular fascial sheath, separating its contents from the other muscle compartments of the tho- Anatomy racoabdominal cavity. The anterior wall of this fascial sheath is incomplete because the sheath The ESP block targets the erector spi- has multiple varied apertures or perforations. nae plane, which lies in the chest wall between Additionally, the sheath is intermittently teth- the anterior surface of the cephalo caudal ori- ered anteromedially to bony structures along ented erector spinae muscles and the posteri- its course, notably the spinous processes and or surface of the spinal transverse processes. transverse processes of the vertebrae it crosses LA is deposited in the fascial plane deep to the [12]. erector spinae muscle and superficial to the tips The key anatomic factors for ESP block of the transverse processes, from where it dif- are not so much the nerves but the associat- fuses to the dorsal and ventral rami of spinal ed ligaments, fasciae, muscles, and bones, for nerves, achieving an extensive multi-dermato- these latter form the compartment into which mal sensory block of the posterior, lateral, and the injection is made and the tissue planes with- anterior thoracic wall [1-8]. in the compartment that determine the spread Anatomically, three muscles trapezius of de LA [9]. (uppermost), rhomboids major (middle), and Some authors have hinted at ESP block erector spinae (lowermost) are identified su- really being a paravertebral block [12,9] due to perficial to the tip of the hyperechoic transverse there are well-described anatomical gaps in the processes. The erector spinae muscle is not intertransverse connective tissue that explain a single muscle, is a structure that forms the how LA can pass from the ESP into the para- paraspinal column, it is a complex composite vertebral space. of three muscles: iliocostalis, longissimus and Luftig et al reported that there are sim- spinalis, that arise from and insert into various ilarities between ESP block and retrolaminar bony components of the vertebral column, for block mainly in the fact that injection occurs deep example, from spinous process to spinous pro- to erector spinae muscle in both instances, and cess, rib to rib, and transverse process to trans- that the retrolaminar block probably also works verse process [9]. It originates from the sacrum via diffusion of LA into the paravertebral space and the lumbar spinous processes, and ex- through the soft tissue gaps between adjacent tends upwards as a gradually tapering column vertebrae. Nevertheless, the retrolaminar block of muscle in the paravertebral groove on either targets the lamina, and the ESP block targets side of the spinous processes, with insertions the transverse process [3]. According to the re- on the thoracic and cervical vertebrae as high sults of the study in cadavers by Yang et al. both as C2. This muscular column is encased in a retrolaminar and ESP blocks were consistently retinaculum (a complex sheet of blended apo- associated with the posterior spread of injectate neuroses and fasciae) that extends from the to the back muscles and fascial layers. Regard- sacrum to the skull base. In the lower back this less of technique, the main route of dye spread 29 Regional Anaesthesia Concept was through the superior costotransverse liga- Furthermore, the ESP block has been ments to the affected paravertebral space. The recently reported to be able to block the sym- ESP block appears to be slightly more favour- pathetic nerve fibers. [17]. However, the mech- able for thoracic spinal nerve blockade than the anism of sympathetic block is unknown. Ueshi- retrolaminar block in the mid-thoracic region ma et al [18] experienced with fluoroscopy in [13]. Additionally, the ESP block produces inter- patients with a ESP block injecting 15 ml of the costals spread as well, which may contribute to radiocontrast agent through the catheter insert- more extensive analgesia in comparison to ret- ed. They investigated the flow and spread of the rolaminar block [14]. local anesthetic. The LA solution spread to the thoracic paravertebral space in all cases and Mechanism of action more than five intervertebral spaces. Follow- ing this, they injected 20 ml of 0.5% lidocaine In the initial report of its description, through the catheter with the subsequent loss the authors demonstrated that injection into the of sensation to pinprick and cold across more fascial plane deep to erector spinae muscle at than five intervertebral spaces and a reduction the level of the T5 transverse process can pro- in pain score in all patients. They concluded that duce an extensive multi-dermatomal sensory the local anesthetic solution may spread to the block which was investigated in fresh cadavers, paravertebral space in the ESP block [18]. for the likely site of action of ESP block, which In fact, the ESP block is considered being dorsal and ventral rami of thoracic spinal as a peri-paravertebral regional anesthesia nerves [1]. technique [19]. The LA is deposited within the Cadaveric data showed that LA inject- erector sheath compartment, the block will be ed into the tissue plane deep to erector spinae successful by distribution of the LA not only muscle and superficial to the transverse pro- cranially and caudally along the sheath, but by cesses and intertransverse connective tissues subsequently gaining access to the paraverte- penetrates anteriorly to anesthetize the spinal nerves [15].